(CNN) -- Sri Lankan security forces have arrested a leader of the defeated Tamil Tiger rebel group and are questioning him, a defense official said Friday.

Sri Lankan Defense Ministry spokesman Lakshman Hulugalle told CNN that Selvarasa Padmanathan is in Sri Lankan custody, but would answer no other questions.

Padmanathan, also known as KP, was the "self-appointed ... leader and chief arms dealer" of the Tamil Tigers, according to Lankapuvath, the national news agency of Sri Lanka. It also reported the arrest, citing the Sri Lankan government information department.

There were conflicting accounts about the circumstances of the arrest.

Sri Lankan state media said authorities arrested Padmanathan in Bangkok, Thailand, but Thai authorities denied that. Tamil sources said Padmanathan was arrested after he left a hotel room to answer a phone call in Kuala Lumpur, Malaysia.

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The Sri Lankan military defeated the Tamil Tigers this year. The rebel group, formally known as the Liberation Tigers of Tamil Eelam, fought a 25-year war seeking an independent state for minority Tamils in Sri Lanka. At least 70,000 were killed.

Remnants of the battered Tamil Tiger group decided in July that Padmanathan would "lead us into the next steps of our freedom struggle," according to a published account.

That happened after the Sri Lankan military killed the group's long-time leader, Velupillai Prabhakaran, in the final days of a bloody offensive that ended the war.